A 100 MHZ TO 1 GHZ VARIABLE GAIN AMPLIFIER IN A 8 GHZ 1.2 MU-M BICMOSPROCESS

A variable gain amplifier with linear gain control has been implemente d in a commercially available 8 GHz 1.2 mu m BiCMOS process. The gain adjustment linearization is based on forcing a linearly controllable c urrent through diode-connected transistors, thus generating an interna l logarithmic control voltage for the Gilbert-type variable gain cell. A Cherry-Hopper type gain stage is used to provide most of the availa ble gain. Thus, the maximum differential gain is 10 dB with over 1 GHz bandwidth and -6.9 dBm input -1 dB compression power. Gain adjustment range of 50 dB at 200 MHz and 38 dB at 960 MHz is reported. The chip area is 1.15 x 2.15 mm and it consumes 40 mA from a 5 V supply.